- to support "old-style" gear/flap control (operation as long as button
pressed/lever pushed -> b29/hurricane), let bindings not only report
up/down, but up (-1), stop (0), down (1).
- let controls.flapsDown() ignore "stop" so as to remain compatible with
prior behavior
- adapt all joysticks/aircraft (sigh)
- some minor cosmetics in joystick configs, such as indentation fixes